A. Field of the Invention
The invention relates generally to redundant switch configurations, and more specifically to redundant switch configurations that provide both signal loss protection and equipment failure protection.
B. Description of the Related Art
For fiber optic networks, problems in transmitting and receiving signals may be due to equipment failure, such as switch failure, or it may be due to failure of the signal lines, such as the fiber optic lines which provide signals from a source to a destination.
Typically, conventional optical communication systems comprise a receiving node and a transmitting node (Baltimore, Md. and New York, N.Y., for example) connected via optical fiber. Each node contains equipment for communication via optical fiber. Such equipment may include channel equipment and Wavelength Division Multiplex (WDM) equipment. Channel equipment is equipment that transmits and receives via a specific wavelength (or channel). In a conventional system, if a fiber is cut resulting in a loss of signal, the system requires a network element (such as a SONET processor) to determine there is a failure in the digital domain and notify the switch to change state.
Further, switches are utilized to direct signals transmitted by the nodes to various fiber optical cables within a conventional optical communication system. When a switch fails in a conventional system, an operator manually reconfigures the switch to communicate via an alternate channel. The resulting down time from manually switching channels results in a high amount of data loss and an inefficient use of backup resources.
The present invention is directed to overcoming or at least reducing the effects of one or more of the problems set forth above, as well as other problems found in the prior art.
In a first aspect of the present invention, a fiber optic system is provided comprising a primary transmission path provided from a source, a secondary transmission path provided from the source, and a network protection unit coupled to the primary and secondary transmission paths provided from the source. The network protection unit comprises a first 1xc3x972 switch, a second 1xc3x972 switch, and a third 1xc3x972 switch.
The first 1xc3x972 switch comprises a first input optically coupled to the primary transmission path, a second input optically coupled to the secondary transmission path, and an output. The second 1xc3x972 switch comprises a second input optically coupled to the primary transmission path, a first input optically coupled to the secondary transmission path, and an output. The third 1xc3x972 switch comprises a first input optically coupled to the output of the first switch, a second input optically coupled to the output of the second switch, and an output optically coupled to an output transmission path.
In a first mode of operation, the first and third switches are set to provide the primary signal to the output transmission path. In a second mode of operation, the first and third switches are set to provide the secondary signal to the output transmission path. In a third mode of operation, the second and third switches are set to provide the primary signal to the output transmission path. In a fourth mode of operation, the second and third switches are set to provide the secondary signal to the output transmission path.
In another aspect of the present invention, a fiber optic system is provided comprising a primary transmission path provided from a source, a backup transmission path provided from the source, and a branch unit provided at a meeting point of the primary and backup transmission paths.
The branch unit comprises a first 2xc3x972 switch, a second 2xc3x972 switch, a third 2xc3x972 switch, and a processor. The first 2xc3x972 switch comprises a first input optically coupled to the primary transmission path, a second input optically coupled to the secondary transmission path, a first output, and a second output optically connected to a detector. The second 2xc3x972 switch comprises a second input optically coupled to the primary transmission path, a first input optically coupled to the secondary transmission path, a first output, and a second output optically coupled to a detector. The third 2xc3x972 switch comprises a first input optically coupled to the first output of the first 2xc3x972 switch, a second input optically coupled to the first output of the second 2xc3x972 switch; a first output, and a second output.
The processor receives information from the detectors regarding the detected signal strength at the second output port of the first 2xc3x972 switch and the second output port of the second 2xc3x972 switch. The first 2xc3x972 switch operates in either a first mode that provides input received on its first input to its first output and input received on its second input to its second output, or a second mode that provides input received on its first input to its second output and input received on its second input to its first output. The second 2xc3x972 switch operates in either a first mode that provides input received on its first input to its first output and input received on its second input to its second output, or a second mode that provides input received on its first input to its second output and input received on its second input to its first output. The processor commands the first and second 2xc3x972 switches to operate in one of the first mode of operation and the second mode of operation, based on the information received from the detectors.
In another aspect of the present invention, a fiber optic system is provided comprising a primary transmission path provided from a source, a backup transmission path provided from the source, and a branch unit provided at a meeting point of the primary and backup transmission paths.
The branch unit comprises a first 2xc3x972 switch, a second 2xc3x972 switch, a detector, and a processor. The first 2xc3x972 switch comprises a first input optically coupled to the primary transmission path, a second input optically coupled to the secondary transmission path, a first output, and a second output. The second 2xc3x972 switch comprises a first input optically coupled to the first input of the first 2xc3x972 switch, a second input optically coupled to the second input of the second 2xc3x972 switch, and an output optically coupled to a main transmission path. The detector is optically coupled to an output of the second 2xc3x972 switch. The processor is in communication with the detector for controlling the first 2xc3x972 switch and the second 2xc3x972 switch.
The first 2xc3x972 switch operates in either a first mode that provides input received on its first input to its first output and input received on its second input to its second output, or a second mode that provides input received on its first input to its second output and input received on its second input to its first output. The second 2xc3x972 switch operates in either a first mode that provides input received on its first input to an output, or a second mode that provides input received on its second input to an output. The processor commands the first 2xc3x972 switch and second 2xc3x972 switch to operate in one of the first mode of operation and the second mode of operation, based on the information received from the detector.
In another aspect of the present invention, a method of providing fiber optic signals on a fiber optical network is provided, the method comprising the steps of providing, from a source, a primary signal on a primary transmission path, providing, from the source, a backup signal on a backup transmission path, receiving the primary and backup signals on the primary and backup transmission paths, respectively, and outputting only one of the primary and backup signals onto an output port that correspond to a main optical path, by way of at least two switches, detecting a signal strength on the main optical path, and determining, based on signal strength or quality, whether or not to operate in a first mode of operation, in which the primary signal is provided to the main optical path, or in second mode of operation, in which the backup signal is provided to the main optical path.